Non-woven papermakers felt

ABSTRACT

An improved non-woven papermakers felt and economical method of manufacturing the same in which a base fabric is formed of a plurality of layers of webs formed of fibers oriented substantially longitudinally consolidated into a homogeneous mass and a web of fibers is needled thereinto.

United States Patent Grieves et al.

[ Nov. 18, 1975 NON-WOVEN PAPERMAKERS FELT Inventors: Lowell G. Grieves,Lacon, 111.;

William S. Wightman, Niskayuna, N.Y.

Assignee: Albany International Corporation,

Albany, NY.

Filed: July 16, 1973 App]. No.: 379,321

Related US. Application Data Division of Ser. No. 205,009, Dec. 6, 1971,

abandoned US. Cl 162/348; 28/722 R Int. Cl. B32b 5/06; D04h 18/00 FieldOf Search 161/57, 58, 60, 69, 80,

[56] References Cited UNITED STATES PATENTS 2,840,881 7/1958 Bateman161/80 X 3,563,838 2/1971 Edwards 161/60 X 3,616,124 10/1971 Danhel161/80 X Primary ExaminerGeorge F. Lesmes Assistant ExaminerA1an T.McDonald [57] ABSTRACT An improved non-woven papermakers felt andeconomical method of manufacturing the same in which a base fabric isformed of a plurality of layers of webs formed of fibers orientedsubstantially longitudinally consolidated into a homogeneous mass and aweb of fibers is needled thereinto.

1 Claim, 6 Drawing Figures US. Patent Nov. 18, 1975 Sheet 1 of33,920,511

US. Patent Nov. 18, 1975 Sheet 2 of3 3,920,511

US. Patent Nov. 18, 1975 Sheet 3 of3 3,920,511

NON-WOVEN PAPERMAKERS FELT This is a division of application Ser. No.205,009, filed Dec. 6, 1971, now abandoned.

BACKGROUND OF THE INVENTION Felts for use in papermaking machines are ofmany varieties and have undergone changes through the years. The wovenversion is the traditional type, developed by weaving the wool orwool-synthetic yarns, and then shrinking or felting the fabric toprovide the appropriate desired finish characteristics and the stablerunning size for the particular paper machine position. Althoughconventional felts are, still used to a great extent, needled felts arebecoming increasingly popular. The standard needled constructionconsists of needle punching a web of fibers into a previously woven basefabric. Although the needled felt has generally been more costly tomanufacture than the conventional wholly woven felt, it has manyadvantagesnot the least of which is the ability to provide in the felt abase having a specific construction and materials selected for aparticular purpose (generally dimensional stability) and combine it witha surface of needled web of fibers formed of different material andhaving its own structure free of the base and selected to provide thedesired surface characteristics in the product being formed.

In conventional needled felt construction the base fabric is woven onthe usual papermakers felt loom. The web is formed by carding fibers andis laid on the base just prior to passing it through the needlingmachine. Several layers of web may be used, the felt going through theneedling machine after each layer is added.

In the needled construction based on paper machine requirements, more orless web can be used on either or both sides of the base fabric, Theneedles are fashioned with tiny barbs. As the needles descend, thesebarbs grasp fibers from the web and force them into the base fabric.

Needled felts are generally stronger. The web contributes strength inaccordance with the orientation of the fibers. As a result of availablemanufacturing procedures, substantially all of the fibers in the web ofconventional needled felts are oriented transversely to the path oftravel of the felt.

Because of the finish problems with regular felts, it is frequently notpossible to add large amounts of synthetics to resist wear. The needledfelts being stronger maintain their bulk, water removal and finishcharacteristics for a longer time than conventional felts.

Another desirable feature of needled felts is improved sheet finish. Thetwisted yarns are hidden in the base and a better and smoother cushionmeets the sheet. The fleecy web needled in provides innumerable veryminute fiber contacts with the sheet, in contrast to the coarser yarncontacts of the wholly woven felt. This smooth surface imparts superiorfinish to one side of the sheet and often improves finish on the otherside, as well by reducing strike-through. Yarns in woven fabrics and inwoven bases of conventional needled fabrics are often objectionablebecause of strike-through or marking of the sheet of paper being formed.

It has been realized for some time that if a completely' non-woven felt(not even a woven base) could be produced without excessive cost andone. which would have sufficient. strength for satisfactory operation,an even superior felt would thus be made available.

SUMMARY OF THE INVENTION A non-woven papermakers felt comprising a baseformed of a plurality of lapped layers of webs of fibers orientedsubstantially in the direction of felt travel and which have beenconsolidated into a homogeneous mass by consecutive compressing andneedling operations, and a web of fibers needled into the base. Thefibers can be synthetic, natural or a blend of synthetic and natural.

A method for producing a non-woven papermakers felt comprising the stepsof: carding a first web of fibers onto a conveyor with the fiberssubstantially parallel and oriented in the direction of movement of theconveyor, delivering the web to a primary lapper and depositing the webon the moving top cart apron with the fibers oriented in the directionof movement of the apron and thence to the lower cart apron, lappinglayers of web from the lower cart apron onto a floor apron with thespeed of the lower cart apron and floor apron adjusted to produce fourfiber layers with the angle of fibers deposited within the range of 85to 45 to the direction of travel of the floor apron, consolidating thefibers into a homogeneous sheet by compressive rub rolls, producing atapered feathered edge on each edge of the sheet by the use of edge combrolls, delivering the sheet to a secondary lapper and depositing thesheet on the moving top cart apron and thence to the lower cart apron,lapping four layers of sheet from the lower secondary cart apron ontothe floor apron with the speed of the lower cart apron and floor apronadjusted to produce four sheet layers with the fibers therein forming anangle with the direction of travel of the floor apronin the range of 10to 40, consolidating the sheet into a homogeneous substrate bypre-needling, providing an endless scrirn netting and feeding thesubstrate onto the scrim and consolidating by passing through a needleloom to form a base fabric, peeling the scrim off the base fabric, andadding web to the base fabric by a needling operation.

An apparatus for producing the non-woven papermakers felt by the saideconomical method.

The method and apparatus disclosed herein provides the ability toproduce a wide, continuous length of web with individual fibers orientedsubstantially in the lengthwise direction. The width of web produced islimited only by the width of available lapping equipment. Felts made inaccordance with this invention do not contain lengthwise or crosswiseyarns, therefore, there will be no yarn marks imparted on the sheet ofpaper. Due to the absence of a woven base fabric, the felt will 7 drainwater better than a conventional felt because of this homogeneity in thefelt; and the absence of a woven base fabric results in a felt whichwill be easier to clean using conventional methods employed on the papermachine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A and FIG. 1B which is acontinuation thereof disclose in perspective view the novel method andapparatus for producing the non-woven base for the felt which is thesubject of this invention;

DESCRIPTION OF THE PREFERRED EMBODIMENT The terms substrate, base andfelt are used herein to designate the product at various stages ofcompletion as will appear.

Also the terms pre-needling" and needling are used as commonlyunderstood in the art. The term preneedling designates a needlingoperation in which fibers are very lightly consolidated to facilitatehandling such as rolling and unrolling. Needling is the operation inwhich fibers are firmly consolidated to produce the product involved. 1

In the method disclosed herein and illustrated in the Figs. a blend ofsynthetic fibers is first carded in a conventional manner on a woolensystem card. The type of blend used has a bearing on the end product.Consideration as to type of polymers, blend percentage, fiber denier andstaple length is pertinent. In one embodiment of the invention thesubstrate is formed of 60 percent, 15 denier, 4 /2 inch polyamid fibersto give strength plus elasticity, 25 percent, 6 denier, 4 /2 inchpolyester fibers to resist stretching and 15 percent, 6 denier, 3 inchpolypropylene fibers which is a fusible material and useful to heat setthe end product.

The carded fibers are doffed from the cylinder doffer 10 in aconventional manner onto inclined conveying apron 11. The weight of theweb doffed in the preferred embodiment is approximately 20 grains persquare foot and the fibers are laid on apron 11 in an essentiallyparallel orientation running in the length direction of the web or inthe direction of movement of the conveyor. The orientation of the fiberson apron 11 is illustrated by exaggerating certain of the fibers anddesignating them by the numeral 12. The carded web is conveyed intoprimary lapper 13. In order to accomplish this the inclined apron 11deposits the web on top apron 14 which deposits the web onto top cartapron 15 of the lapper and thence to lower cart apron 16. The web asdeposited on the moving top cart 15, has the fibers thereof oriented inthe direction of movement of the apron as illustrated in FIG. 1A by thearrow 15. The web is lapped by layers in lapper 13 from the lower cartapron 16 onto floor apron 17 with the speed of the lower cart apron andfloor apron adjusted to produce four fiber layers with the angle offibers deposited within the range of 85 to 45 to the direction of travelof the floor apron. Again in FIG. 1A, the orientation of the fibers onthe floor apron is illustrated by exaggerating the fibers anddesignating them by the numeral 18. In the apparatus, the lower cart 16travels from left to right and then right to leftorto-and-fro-depositing the layers of web on the moving floor apron. Thewidth of the web lapped onto the floor apron is approximately 80.5inches in one example and consists of four layers of the web and theangle of fibers deposited being approximately 75 to the direction oftravel of the floor apron. The four layers of web thus deposited arethen consolidated into a homogeneous sheet of fibers by means ofcompressive rub rolls 19, 20 and 21. By this means the four layers ofweb are prevented from ply separating in subsequent processing. Thesheet so produced is designated in the Figs. by the numeral 22. Thissheet is then taken up by the first intermediate apron 23 and fedbetween vertical aprons 24 and 25.

During the process of conveying the four layers of web from the floorapron to the first intermediate apron 23, the web is draftedapproximately l.74 times 4 or 74% by varying in speed of the rub rollsand aprons. This results in the angle of fibers being reduced toapproximately 66 to the direction of travel.

The sheet is transported between the vertical aprons 24 and 25 to thesecond intermediate apron 26 which is shown in FIG. 1B.

From the second intermediate apron 26 the sheet is conveyed by means oftop apron 27 to a stationary turning device 28. The surface of thisstationary turning device 28 should be slippery and the device can bemade of highly polished stainless steel, teflon, or any othermaterial'which would provide such slippery surface. The sheet, afterturning, is deposited upon feedthrough apron 29 and transported tosecondary lapper 30.

An intermediate step in the process is to remove the folded-over edgesof the sheet by means of edge combing devices 31 and 32. The fiberremoved by these edge combing devices on each edge are conveyed byblowers and a pipe system, not shown, back to the card-feeders. With thefolded-over edges removed by the edge comb rolls, a tapered-featherededge remains on the sheet.

The secondary lapper 30 operates in a similar manner to the primarylapper 13 except that very wide widths can be developed in the secondarylapper. In one example, lap widths up to 400 inches were made. There isno limit to the width that can be made provided a sufficiently widelapper is available.

In the secondary lapper, the sheet is deposited on the secondary topcart apron 33 and thence to the secondary lower cart apron 34 and thenonto the secondary floor apron 35.

Four layers of web had been lapped in the primary lapper to produce asheet. Now four sheets are lapped in the secondary lapper to produce asubstrate on secondary floor apron 35 consisting of a total of sixteenoriginal fiber layers.

' Thesheets are laid onto the floor apron with the speed of the lowercart apron and the floor apron adjusted to produce the four sheet layerswith the fibers therein forming an angle with the direction of travel ofthe floor apron in the range of 10 to 40. The width of the laps formedis infinitely variable within the ranges available in the machine and inthe specific example 'disclosed herein the width of the laps thus formedis variable within the ranges of I00 inches minimum and 400 inchesmaximum. For the IOO inch width the fibers are aligned at approximately13.5 and 345 to the direction of travel and for the 400 inch width thefibers are aligned at approximately 21.5 and 26.5 to the direction oftravel.

In order to consolidate into a homogeneous substrate, the sheet iscompressed and passed through preneedling machine 37. The compressionprior to preneedling can be accomplished by any suitable means. In thepresent application the bed plate 37 of the preneedler is extendedtoward apron 35 and a plate 36 which is a compacting sheet of metal ismounted over the bed plate 37 on the top side of the sheet. As thesubstrate passes between plates 36 and 37', it is compressed. Thesubstrate so formed and indicated by the numeral 38 in the Figs. ispassed to wind up mechanism 42 where rolls of the substrate are producedfor subsequent use in further processing. The example of the embodimentdisclosed herein allows for the production of long lengthsof substrateup to 200 feet in length on the rolls. This is not a limit but rather anexample.

These rolls of substrate have the fibers oriented essentially in thelength direction giving the substrate more resistance to stretchlengthwise than crosswise. Weight of the substrate produced varies fromI80 grains per square foot to 225 grains per square foot. Lighter orheavier substrates could also be made but would depend upon theanticipated end use. In the present stage of the art heavier substratesmay not be useful for papermakers felts, however, they may be desirablefor other types of non-woven industrial textiles such as corrugatorbelts or conveyor belting.

In the next step in the process, which is illustrated in FIGS. 2A, 2Band 2C, an endless scrim 43 is installed between rollers 44 and 45 andlightly tensioned. In one example the scrim is formed of light weightpolypropyl ene netting in endless form and of proper length and width toproduce a wet felt. Another type of scrim can be used if desired to holdthe substrate together during the needling operation which isaccomplished in the needle loom designated by the numeral 46 in FIGS.2A, 2B and 2C.

The lengthwise oriented substrate 38 is then unwound from roll 47 ontothe scrim netting and consolidated by passing through the needle loom46. Three layers are shown being needled in in FIGS. 2A, 2B and 2C. Thefirst layer after passage through the needle loom 46 is a needled inlayer indicated by the numeral 38a. The next step illustrates the scrim43 with layers 38a and 38b and the third or final step illustrates thescrim 43 with layers 38a, 38b and 38c needled thereinto.

Once these three layers have been sufficiently consolidated by needlingso that they become self-supporting, the initial scrim 43 is peeled awayfrom the inside to provide the base fabric. This base fabric is anendless loop of the proper length, width and strength for subsequentprocessingfOnto this base are applied further layers of fibers which arelapped in a conventional manner as a web with fiber orientationessentially crosswise to the length direction of the felt and there isprovided subsequent consolidation by needling as illustrated in FIG. 3wherein the base 38a-38b-38c is shown passing through needling machine48 after multiple layers of conventional web from roll 49 have beenplaced thereon. In FIG. 3 the needling machine designated by 6 thenumeral 48 could also be the machine previously designated in FIGS. 2A,2B and 2C by the numeral 46.

After completion of needling the felt is washed in a conventional mannerand then stretched to its proper operating tension and length on aconventional felt dryer. During the lengthwise stretching the fibers inthe base which had been at angles to the lengthwise direction as aresult of the first and second lapping operations are orientedsubstantially lengthwise. In one ex ample, after stretching theresulting length of the felt is 108% of the length prior to stretching.The felt is dried by means of heated cylinders (such as steam heated,gas heated or otherwise) as is well known in the art.

In certain embodiments, after drying, the felt is subjected to a heattreatment in the neighborhood of 380F which tends to fuse thepolypropylene fibers previously referred to. This fusing tends tofurther stabilize the fabric. Another alternative for further bondingand stabilization dimensionally is to use resin treatments but thesetend to make the finished products stiff and impede easy installation incertain positions on the paper machine.

In FIG. 1A feed-through apron 29 is shown in phantom. Conveying apron 11is also shown in phantom in a shifted position. The apparatus is soconstructed with apron ll shiftable between two positions so that whenit is desired to make a conventionalweb with fibers oriented crosswise,it is necessary only to shift apron 11 from the position shown in solidlines to the position shown in phantom in FIG. 1A where it can feed thefibers received thereon directly onto feed-through apron 29 therebyby-passing the first lapping operation.

We claim:

1. A non-woven papermakers feltwhich comprises a substrate formed of aplurality of lapped layers of webs of fibers oriented substantially inthe direction of felt travel and which have been consolidated into ahomogeneous mass in the absence of bonding and stitching by consecutiveneedling operations wherein the weight of the substrate is within therange of 180 grains per square foot to 225 grains per square foot; and aweb of fibers needled into said substrate substantially crosswise ofsaid felt travel.

1. A NON-WOVEN PAPERMAKERS FELT WHICH COMPRISES A SUBSTRATE FORMED OF APLURALITY OF LAPPED LAYERS OF WEBS OF FIBERS ORIENTED SUBSTANTIALLY INTHE DIRECTION OF FELT TRAVEL AND WHICH HAVE BEEN CONSOLIDATED INTO AHOMOGENEOUS MASS IN THE ADSENCE OF BONDING AND STITCHING BY CONSECUTIVENEEDLING OPERATIONS WHEREIN THE WEIGHT OF THE SUBSTRATE IS WITHIN THERNAGE OF 180 GRAINS PER SQUARE FOOT TO 225 GRAINS PER SQUARE FOOT; AND AWEB OF FIBERS NEEDLED INTO SAID SUBSTRATE SUBSTANTIALLY CROSSWISE OFSAID FELT TRAVEL.